package cn.trigram.example.designpattern.iterator;

import java.util.Arrays;

//方便演示而实现的简陋的数组list
public class MyArrayList<T> implements MyList<T> {
	private int size;				//存放的元素个数,会默认初始化为0
	private Object[] defaultList;	//使用数组存放元素
	private static final int defaultLength = 10;//默认长度
	public MyArrayList(){				//默认构造函数
		defaultList = new Object[defaultLength];
	}
	@Override
	public MyIterator<T> iterator() {
		return new Iterator();
	}
	//大小自动增长
	private void ensureCapacity(int capacity){
		int nowLength = defaultList.length;
		if(capacity >= nowLength){
			nowLength = nowLength + (nowLength>>1);
			if(nowLength<0)//溢出
				nowLength = Integer.MAX_VALUE;
			defaultList = Arrays.copyOf(defaultList, nowLength);
		}
	}
	//添加元素
	@Override
	public boolean add(T t) {
		ensureCapacity(size+1);
		defaultList[size++] = t;
		return true;
	}
	//获取元素
	@SuppressWarnings("unchecked")
	@Override
	public T get(int index) {
		if(index<0 || index>=size) return null;
		return (T) defaultList[index];
	}
	@Override
	public T remove() {
		return remove(size-1);
	}
	@SuppressWarnings("unchecked")
	@Override
	public T remove(int index) {
		if(index<0||index>=size) return null;
		T element = (T) defaultList[index];
		if(index != size-1)
		System.arraycopy(defaultList, index+1, defaultList, index,size-index-1);
		size--;
		return element;
	}
	@Override
	public boolean remove(T element) {
		if(element==null){
			for(int i = 0 ; i<size;i++)
				if(defaultList[i]==null){
					System.arraycopy(defaultList, i+1, defaultList, i,size-i-1);
					size--;
					return true;
				}
		}
		else{
			for(int i = 0 ; i<size;i++)
				if(defaultList[i].equals(element)){
					System.arraycopy(defaultList, i+1, defaultList, i,size-i-1);
					size--;
					return true;
				}
		}
		return false;
	}
	@Override
	public boolean set(int index,T element) {
		if(index<0||index>=size) return false;
		defaultList[index] = element;
		return true;
	}
	@Override
	public int size() {
		return size;
	}
	//迭代器
	private class Iterator implements MyIterator<T> {
		private int next;
		@Override
		public boolean hasNext() {
			return next<size;
		}
		@SuppressWarnings("unchecked")
		@Override
		public T next() {
			return (T) defaultList[next++];
		}
		@Override
		public T remove() {
			// TODO Auto-generated method stub
			return null;
		}
	}
}